Cementitious compositions and methods



3,511,313 CEMENTITIOUS COMPOSITIONS AND METHODS Louis H. Eilers and Christ F. Parks, Tulsa, Okla., as-

signors to The Dow Chemical Company, Midland, Mich., a corporation of Delaware No Drawing. Filed Sept. 10, 1965, Ser. No. 486,530 Int. 'Cl. E21b 33/14; C08f 45/22, 45/34 US. Cl. 166-295 6 Claims ABSTRACT OF THE DISCLOSURE Thesealing of void spaces, eg as in geological formations and/ or between metal shapes is accomplished with a liquid slurry of a particulate, water-soluble organic polymer in an organo solvent. The mixture of the polymer and solvent has a controlled set time to allow the emplacement of the slurry as a liquid. The slurry then sets to form a sealing cementitious material. Depending upon the class of organo solvent employed, the set time of the slurry is controlled by temperature manipulation, mixing the organo solvent with a second organic liquid of, different solvency properties or mixing with water.

The present invention concerns preparing and using cementitious formulations of soluble organic polymers and certain organo solvents for the polymers. In one jinited States Patent aspect, the invention relates to the use of such compositions in cementing applications. Another aspect concerns methods for accomplishing the foregoing; especially controlling the set times of the formulations.

The present invention provides a novel approach to a variety of cementing needs. It is particularly beneficial for use in geological formations. The formulations described herein set to hard gels of excellent strength properties and with adhesion to a large number of substrates. Control of the set times of the cementitious formulations permits convenient application of the compositions as readily flowable liquids. Particular uses of the gels include sealing oil well boreholes, cementing well casings to adjacent formations and coating geological formations to render them impermeable to fluids.

In general, the method of the invention comprises applying to void space defined by solid surfaces a liquid slurry of a particulate, water-soluble, organic polymer and an organo solvent therefor and maintaining the liquid mixture in such void space until it has hardened into a shape retaining gel, i.e., set.

The terminology water-soluble organic polymer, as used herein refers to nonionic, anionic, cationic or ampholytic organic materials composed of a number of repeating units or mers. The useful polymers are characterized by dispersibility in water to form visually continuous solutions or dispersions. This includes truly Watersoluble polymers which disperse in water to provide homogeneous, transparent solutions subject to water dilution without phase separation. Also included within the meaning of water-soluble, as used herein, are the water-swellable polymers which readily disperse in water to provide a highly disperse and visually continuous system of individually distinct, gelparticles.

Organo solvents useful in the invention fall into three general classes. Each class is characterized by unique gel forming characteristics and in the properties of the final hardened gel. Although the organo solvent used may consist of only organic materials it may also be mixed with water, or, in fact, any desired liquid material compatible with the solvent to produce a variation Within the invention. As used herein the term organo solvent refers to a homogeneous liquid composed substantially of an organic material, that is, it contains no more than about 50 percent by weight of water, which organo solvent is absorbed by the particulate polymer to form a continuous phase.

The first class of organo solvents useful in the invention, hereinafter termed Group I solvents, are the liquid organic solvents which solvate or plasticize solid, watersoluble polymers. That is, the polymers, if they are not totally miscible with the solvent, absorb a significant proportion of the same. Solvents of this nature, suitable for use with a wide variety of water-soluble polymers, in- V dude for example ethylene glycol, ethylenediamine, glycerol, dioxolane, formamide, pentaerythritol and acetic acid. Some materials may not function as solvents at normal room temperatures but can be activated as sol vents for most water-soluble polymers at elevated temperatures. Such materials include diethylene glycol, dipropylene glycol, diethanol amine, monoethanol airline, propylene glycol, triethylene glycol, diethylenetriamine and triethanolamine.

A second class of useful organo solvents, hereinafter termed Group II solvents, includes a large number of organic materials which are not solvents for the polymers (non-solvents), i.e., they do not solvate or plasticize the water-soluble polymers to form a continuous phase, but which, when mixed with a small amount of Water, produce organo solvents useful for the purpose of the invention. Manifestly, such materials must be miscible with water. It has been found that as little as 1 percent by weight water dissolved in an organic liquid, which is not a solvent for the polymer, often renders the resulting mixture a suitable organo solvent for the purposes of the invention. Sometimes the organic material may normally exist as a solid. In such instances, enough water, e.g., up to 50 percent by weight of the total solvent composition may be used to provide a liquid solution of the organic material. The resulting aqueous solution is an organo solvent suitable for the purposes of the invention. Since the set time of a formulation is decreased by increases in the water content of the organo solvent used, the amount of water is usually maintained at less than about 25 percent by weight of the total solvent composition.

Materials which are not normally solvents for the watersoluble polymers, but which on addition of water become such solvents at room temperature, e.g., F., include diethylene glycol, dipropylene glycol, diethylene glycol monomethylether, ethylene glycol monoethylether, dioxane, ethylene carbonate, ethanolamine, triethylene glycol, propylene glycol, sucrose, urea, dextrin, diethanol amine, triethanol amine, and diethylene triamine. A most useful class of organic materials for formulating Group II solvents includes the liquid alkylene oxide polymers, which are notrsolvents in themselves for the water-soluble polymers. Such alkylene oxide polymers include, in addition to those mentioned above, higher polymers of ethylene oxide having molecular weights up to as much as 600 or so. Liquid propylene oxide polymers include tripropylene glycol, tetrapropylene glycol and higher propylene oxide polymers having molecular weights up to as much as 1200 or so. In addition, water-soluble alkyl and aryl monoethers of the alkylene oxide polymers can form useful solvents when mixed with water. Exemplary alkyl and aryl etherifying groups include methyl, ethyl, propyl, butyl, dodecyl, phenyl, butylphenyl and the like groups.

A third class of organo solvents, hereinafter termed Group III solvents, is composed of mutual solutions of an organic material, which is not solvent for the water-soluble polymers, and an organic material, which is a solvent for the polymer, i.e., a Group I solvent. In such mixtures, at least about 0.05 part of the polymer solvent is employed for each part by weight of the non-solvent. Such organs solvents allow convenient adjustment of the set times in non-aqueous cementitious formulations by increasing or decreasing the amount of polymer solvent relative to the non-solvent.

Controlling the set times, or in other words gel times, of water-soluble polymer-solvent mixtures, wherein the organo solvent classifies with Group I solvents, is achieved through temperature control. The temperature of the polymer-solvent mixture is decreased to a point at which gelation occurs after a given period of time as the temperature of the system equilibrates with its environment. The formulation temperature is most conveniently controlled by adjusting the temperature of the organo solvent.

In some instances, a cementitious formulation requires temperatures higher than room temperature in order to achieve a set. Examples of such solvents operable as the sole solvent only at higher temperatures have been described hereinbefore. Illustratively, diethylene glycol, propylene glycol and dipropylene glycol and diethanol amine are effective if utilized at temperatures above about 100 F. Formulations prepared with such organo solvents are most useful, with their long shelf lives, for grouting and sealing subterranean geological formations which normally exist at temperatures above 100 F. or so.

The set times of formulations prepared with Group II solvents can be adjusted by the proportion of water incorporated into the organic materials which are non-solvents for the polymers. As little as 0.5% by weight water, based on the total organo solvent, will appreciably shorten the set time of the formulation. Unless the polymer nonsolvent requires a higher proportion of water to exist as a liquid, it is generally not desirable in the interest of providing longer set times to utilize more than 25% by Weight Water based on the weight of the total organo solvent.

The set times of formulations prepared with Group III solvents are controlled by the proportion of organic polymer solvent utilized conjunctively with the organic, polymer non-solvent. With increases in the amount of solvent in relation to the non-solvent, the set time is decreased. Organo solvents of this type are preferred for use in applications where control of set times cannot be achieved by control of temperature and a non-aqueous cement is desired.

The water-soluble, particulate organic polymers useful herein are available in a wide variety of chemical composition. They may be obtained as natural polymeric products, by modification of natural polymers or by synthesis from polymerizable materials.

Water solubility is imparted to such polymers by the; presence in and along the polymer chain of a number of hydrophilic moieties sufiicient to more than offset the otherwise hydrophobic character of the organic polymer. One class of such hydrophilic moieties includes the ionizable groups. Among these are the sulfate and sulfonate groups, carboxylate salt groups, amino and ammonium groups, the latter being inclusive of protonated as well as quaternary derivatives of the amines, e.g., mono-, diand trialkyl substituted ammonium salt groups, and phosphoric acid groups and monoand dibasic salts thereof. Whenever acid salts are referred to, those generally intended are the alkali metal, alkaline earth metal (water-soluble species thereof) and ammonium salts.

Another class of water-solubility imparting, hydrophilic moieties are such non-ionizable groups as carboxamide, and monoand dialkyl N-substituted carboxamides, having a total of up to about 8 carbons. Also of a hydrophilic nature, though less strongly than some of the aforementioned groups are, hydroxyl, acetal, ketal, carbamate and lactam groups. In any event, the polymers employed herein contain one or more of the aforedescribed hydrophilic moieties, and the like, in and along the polymer chain in a sufiicient amount to render the resulting polymer watersoluble as defined above.

The polymers used in the invention are characterized by a high molecular weight. An adequate molecular Weight i shown if the polymer can. be obtained as a particulate solid and a 2 percent by weight solution of the polymer in water, at a pH of 7, has a viscosity measured with a Brookfield viscosimeter at 25 C., of at least 10 centipoises.

Technology for preparing the water-soluble polymers useful herein is known. Useful ethylenically polymerized polymers are described in Hedrick et al., US. Pat. 2,625,529, Aimone et al., US. Pat. 2,740,522 and Booth et al., US Pat. 2,729,557. A variety of water-soluble polysaccharide derivatives are described in Gloor, US. Pat. 2,728,725. Water-soluble polyurethanes or chain extended polyols are taught in Honea et al., U.S. Pat. 3,054,778 and a variety of polycarbamates and polylactams in Hibbard et al., US. Pat. 3,044,992, Walles et al., US: Pat. 2,946,772, Vitales, US. Pat. 2,874,124 and Fong et. al., US. Pat. 3,000,830. These are to mention but a few of the well-known chemical avenues for the preparation of Water-soluble, particulate macromolecules. Further general descriptions of a variety of Water-soluble, particulate macromolecules is contained in Davidson and Sittig, Water-Soluble Resins, Reinhold Publishing Corp., New York, 1962.

Preferred for use herein are water-soluble carbamoyl polymers. The most common forms of these are ethylenically polymerized polymers having attached along their polyalkane backbone a plurality of carbamoyl groups according to the formula:

wherein R and R are independently selected from the group of hydrogen and alkyl hydrocarbons with 1 to 4 carbons.

In particular, useful carbamoyl polymers include the various water-soluble homopolymers and copolymers of acrylamide and methacrylamide. Other carbamoyl polymers are the various water-soluble copolymers of N-substituted acrylamides such as N-rnethyl acrylamide, N- propyl acrylamide and N-butyl acrylamide. Still other carbamoyl polymers are prepared from the amides and half amides of maleic and fumaric acids. In general, any ethylenically unsaturated and polymerizable monomer, which contains the carbamoyl group, may be employed in the preparation of the preferred carbamoyl polymers.

Best results are obtained, if at least about 25 mole percent of the polymerized mers have carbamoyl substituents. The balance of the comonomers used to prepare the copolymers can be provided in the form of any watersoluble, or water-insoluble, monoethylenically monomer copolymerizable therewith, so long as the total amount of water-soluble monomers used is sufficient to impart water-solubility to the finished polymer.

Other water-soluble polymers useful herein are the lightly cross-linked water-swellable polymers. Such crosslinking can be achieved by irradiation of linear, watersoluble polymers under conditions which promote crosslinking or by incorporating a small amount, e.g., up to 1% by weight, of a polyfunctional monomer into the polymerization recipe for a linear water-soluble polymer. Examples of such monomers, which may be copolymerized with monoethylenically unsaturated monomers, are

methylenebisacrylamide, divinylbenzene, divinylether, di-' vinylether of ethylene glycol and the like.

In preparing the cementitious gels of the invention, it is best to add the polymeric ingredient to the organo solvent. The organo solvent is prepared first, if there is more than one material involved, to provide a uniform liquid medium. If temperature is to be relied upon to control the set time, the organo solvent is adjusted to a desired temperature. Subsequently, a particulate form of the water-soluble, solid organic polymer is incorporated into the liquid mixture. The mixture is supplied with sufficient agitation to suspend or slurry the polymer in the organo solvent. The resulting liquid slurry is then placed in the void to be sealed. Ultimately the slurry produces a shape retaining gel which tenaciously adheres to its solid environment.

The strength of the final set composition is controlled in part. by the amount of the polymer used. Useful strength properties are often achieved by incorporating into the organo solvent at least about 0.1 part by weight of the polymer per part by weight of the solvent. In any event, at least enough of the polymer is used to achieve gelation of the composition. This can be insured by employing at least about 0.5 part by weight of the polymerper part by Weight of the organo solvent. The upper limit of polymer usage is controlled only by the need to provide a flowabl'e'liquid slurry. Generally, no more than about 2 parts by weight of the polymer per part by weight of the solvent are used.

Mixing of the ingredients is readily achieved using conventional solids-liquids mixing devices. Emplacement of the resulting fluid admixture is achieved by any of the usual. liquid slurry handling means. For instance, ordinary centrifugal pumps are satisfactory for pumping the slurry. If needed, the slurry is easily maintained in the void space to be sealed until it sets by suitable confining forms and/ or suitably applied fluid pressure.

In a special embodiment of the invention, the cementitious. composition of the invention has been discovered to be further enhanced with respect to its properties, especially its cohesive strength, by incorporating into the composition an oxide, hydroxide or salt of a polyvalent metal. Specific oxides, hydroxides and salts, all of which must have some solubility, however slight, in the liquid phase, include those of the following metals: calcium, magnesium, zinc, ferric, aluminum and the like. Useful salts include the chlorides and sulfates of these metals.

The use of from about 0.05 percent up to a maximum of about 12 percent based on the weight of the polymersolvent compositions, of one or more of the aforementioned inorganic materials increases substantially the yield strength or cohesiveness of the finally set cementitious compositions of the invention.

When set, the formulations of the invention provide tough fluid. barriers with good adhesion to a wide variety of substrates, specifically including most geological formations, especially siliceous formations. Once set, the cementitious compositions of the invention are relatively impervious to water. They will imbibe water when in contact with aqueous media, but if confined, as within a formation or well casing, they will not lose their strength properties even after prolonged contact with aqueous media.

The following examples provide further illustration of the invention.

EXAMPLE 1 stirred into the ethylene glycol to produce a uniform blend at about 75 F. (approximate room temperature). The composition set to a shape retaining, rubbery gel in minutes.

The set gel is useful as a cement in a variety of oil well treating applications. In a specific use, a slurry prepared as described above is placed in the annulus defined by two concentric oil well casings. When set, the composition provides a highly adherent and persistent annular seal.

To illustrate set time control with Group III organo solvents, a second formulation was prepared with a /50 mixture of ethylene glycol and diethylene glycol, which are a solvent and non-solvent for the polymer respectively. To 100 milliliters of this mixture at 75 F. was added 75 grams of the above polymer. After about 4 hours, the composition achieved an initial set to produce a solid, rubbery cement. By way of comparison, 75 grams of the polymer in 100 milliliters of diethylene glycol remained fluid through 48 hours, after which the test was terminated.

Through the conjoint use of the non-solvent and solvent to prepare the organo solvent, the set time of the composition was extended by over 3 hours. The longer set time permits batchwise preparation of the formulation and otherwise more extensive handling thereof prior to use.

EXAMPLE 2 To exemplify the metal surface adhesion of cementitious compositions prepared in accordance with the invention, a quantity of the formulation in the above example prepared with the Group III solvent was poured into a vertically aligned pipe, the lower end of which was plugged with a rubber stopper. The composition was allowed to cure for about 20 hours at 75 F. In a second run, the temperature was increased to 150 C. In this manner, plug seals about 12 inches long were produced in each pipe. The set time of the composition at these temperatures was determined as the length of time required for the organo solvent-polymer slurry to form a shape retaining mass.

To measure seal quality, the upper end of the pipe was fitted with a high pressure cap and the rubber stopper removed. Nitrogen gas was applied gradually to the seal until it failed or withstood the maximum pressure for 10 minutes. The maximum pressure applied with this technique was 1,000 pounds per square inch.

In still further runs similar to the above, a series of compositions were prepared in which portions of the polymer were replaced with corresponding amounts of magnesium hydroxide. The curing and testing conditions were as discussed above.

The compositions, set times for cures at 75 F. and 150 F., and adhesion strength properties for the above This example illustrates formulating cementitious gels operations are included in the following table:

TABLE 1 Formulation Properties Carbamoyl Ethylene Dietliylene Yield Set Time (l1rs.)

Polymer Glycol Glycol Mg(OH)2 Strength (gins) (1111.) (ml) (gm.) (p.s.i.) 75 F. 150 F.

according to the invention using Group I and Group II EXAMPLE 3 organo solvents. To 100 milliliters of ethylene glycol at a temperature of F. was added 75 grams of a particulate carbamoyl polymer. The polymer was a polyacrylamidein which about 7 percent of the initially available carboxamide groups had been hydrolyzed to sodium carboxylate groups. It was characterized by a molecular Gel times for polymer-solvent mixtures of the invention were ascertained according to the procedure set forth in section 9, schedule 6, of API-RP 10B, 12th ed., March 1963. Basically, the procedure involved using the thickening time tester as therein described. The test device was charged with a polymer-solvent system to be tested.

wei ht of at least about one million. The polymer was 75 In these operations. the formulations were heated in a maximum of 144 F. in 36 minutes during which time continuous viscosity measurements were made. Thickening or gelation set times were measured as the elapsed time between starting the heating of the formulation and the occurrence of a slurry consistency of 100 poises. The thickening times of several formulations are set forth in the following Table 2.

The formulations tested include a polyacrylamide having a molecular weight of at least about one million mixed with each ethylene glycol and diethylene glycol, and mixtures of the two glycols. Sixty grams of the polymer were slurried in 100 milliliters of the particular organo solvent used. The results of these tests are set forth in the following Table 2.

Of the above runs, run number 3 is a preferred formulation for employment in a well with a bottom hole tem- 8 EXAMPLE 5 Although water-soluble carbamoyl polymers are preferred for use in the invention, useful cementitious compositions can be formulated from any of a wide variety of other types of water-soluble organic polymers. To illustrate the general applicability of the invention, exemplary species of natural gums, natural proteins, polysaccharide derivatives, vinyl polymers other than carbmoyl polymers, polyurethanes and polyethylene oxides were evaluated with each of three organo solvents. All of the polymers tested, were characterized by high molecular weights as hereinbefore defined. Representative of Group I solvents were ethylene glycol and ethanolamine. Representative of Group II was a 66% by weight solution of sucrose in water.

The polymer being evaluated was added to 50 milliliters of the organo solvent in small increments until a definite increase in slurry viscosity was apparent. This amount of polymer was then mixed with 50 milliliters of the solvent first at 80 F. and, if no set resulted within 48 hours, again with the solvent at 150 F.

The amounts of polymer used to produce a gel and the temperature at which gelation was obtained are set forth in the following table along with the set time of the parperature of 144 F. The set time of 49 minutes allows ticular composition in hours.

TABLE 4 Ethylene Glycol Monoethanol Amine 66% Sucrose in Water Polymer Cure Polymer Cure Polymer Temp. Amt. Set Time Temp. Am Set Time Temp. Amt. Set Tim Water-Soluble Polymers F-) (e F) (em (em G 80 34 24 150 0.25 80 20 0 1 K igyg i nn 80 39 0. 25 80 44 0. 25 80 0 1 Tragacanth gum. 39 0. 25 80 42 0. 25 80 17 0 1 Zein 80 31 1 NS 80 25 0. 1 150 17 24 Gelatin- 80 43 0. 25 80 38 0. 25 80 19 4 Corn starch 80 45 NS 80 49 0.25 150 26 s Carboxymethyl cellulose 80 87 4 150 28 NS 80 17 0 1 Sodium polylstyrene sulfonate 80 13 0. 1 80 33 0. 25 80 7 0 25 l -N- rolidone zvzater s i v ell le) 80 25 0. 1 80 33 0. 25 80 15 0, 25 P l th 2 150 34 0. 25 150 35 NS 80 24 48 Polyethylene oxide 150 14 0. 25 150 18 NS 150 13 24 PolyVinyla-lcohol 150 8 N s 80 27 24 80 14 N S Vinylacetate-maleic half amide copolymer- 80 39 0. 5 80 35 NS 150 15 24 1 NS means not satisfactory as the result of poor final properties, e.g., the product crumbles or there is no gel formation at all. 2 This is the reaction product of a polyglycol of 10,000 average molecular weight and a small amount of toluene d1-1socyanate.

suificient opportunity for placing the composition in the well prior to its setting and thus becoming unworkable.

EXAMPLE 4 TABLE 3 Wt. Gel Time (hours) at Specified percent Temp., F

Water Organo Solvent Added 80 200 Diethylene glycol 10 4 2 1 0. 5 16.6 0.7 0.5 0.3 Triethylene glycol 0 Propylene glycol Dipropylene glycol Diethanol amine What is claimed is:

1. A method for forming a pressure retaining seal between a casing and an adjacent geological formation penetrated by the casing which comprises introducing into the zone in which the pressure retaining seal is desired a liquid slurry comprising a water-soluble organic polymer and an organo solvent therefor, which slurry sets into a gel, said polymer being employed in an amount from about 0.1 to 2' parts by weight thereof per part by weight of organo solvent, and said polymer being characterized by a viscosity, in 2 percent water solution, of at least 10 centipoises.

2. A method as in claim 1 wherein the water-soluble polymer is a carbamoyl polymer characterized as having along its backbone a plurality of carbamoyl groups according to the formula:

wherein R and R are independently selected from the group of hydrogen and alkyl hydrocarbons with 1 to 4 carbons.

3. A method as in claim 1 and including the additional step of lowering the temperature of the organo solvent to produce a desired set time.

4. A method for sealing void space defined by solid surfaces which comprises filling in the void space with a liquid slurry comprising a solid, water-soluble organic polymer and an organo solvent for the polymer, which slurry sets into a gel, said polymer being employed in an amount from about 0.1 to 2 parts by Weight thereof per part by weight of organo solvent, and said polymer being characterized by a viscosity, in 2 percent water solution, of at least 10 centipoises and said organo solvent being composed of a liquid mixture Of an organic non-solvent for theWater-soluble organic polymer, which non-solvent is miscible with water, and a small amount of water sufficient, to render the liquid mixture a solvent for the polymer, and adjusting the amount of water employed to produce a predetermined set time for the liquid slurry of polymer solids and organo solvent.

5. A method for sealing void space defined by solid surfaces, which comprises filling in the void space with a liquid slurry comprising a solid, water-soluble organic polymer and an organo solvent for the polymer, which slurry sets into a gel, said polymer being employed in an :amountfrom about 0.1 to 2 parts by weight thereof per part by weight of organo solvent, and said polymer being characterized by a viscosity, in 2 percent water solution, :of at least 10 centipoises and said organo solvent being a liquid mixture of an organic non-solvent for the water-soluble organic polymer and an amount of at least 0.05 part by weight, per part by weight of the non-solvent, of, an organic solvent for the polymer miscible with the non-solvent for the polymer, the amount being suflicient to render the liquid mixture a solvent for the polymer, and adjusting the amount of the organic solvent employed to, produce a predetermined set time for the liquid slurry of polymer solids and organo solvent.

6. A method for sealing void space defined by solid surfaces which comprises filling in the void space with a liquid slurry comprising a particulate, water-soluble carbamoyl polymer in a gel forming organo solvent therefor which slurry sets into a gel, said slurry containing from about 0.1 to about 2 parts by weight of the polymer per part by weight of the organo solvent and from about 0.05 up to 12% by weight of a finely divided magnesium hydroxide or calcium chloride, said carbamoyl polymer being characterized as having along its backbone a plurality of groups according to the formula:

wherein R and R' 'are independently selected 'from 'the group of hydrogen and alkyl hydrocarbons with 1 to 4 carbons.

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